Cluster group of genes preferentially expressed in pericarp [cluster 1(1)] and both in pericarp and endosperm fractions [cluster 1(2)]. Fine clustering using K-means of individual clade of hierachical output resulted in identifying cluster groups. Expression values are given in logarithmic scale (base 2): red-high expression; yellow-moderate expression; blue-low expression. Each individual gene is represented as horizontal row and developmental stages are described in vertical columns. Overall, gene expression data obtained from 3 cultivars are shown: cultivar 'Barke' (B), 'Morex' (M), 'Golden Promise' (GP). Gene expression data covering independent replications are shown in Additional file 3.